Programmer Guide/Command Reference/EVAL/qinterp: Difference between revisions
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{{DISPLAYTITLE:{{SUBPAGENAME}}}} | |||
Compute interploated coordinates of local peaks of a function using 2nd order interpolation. | |||
;Usage: | |||
:<code>qinterp(<var>dx</var><sub>scalar</sub>, <var>y</var>, <var>ip</var> {, <var>nwidth</var>})</code> | |||
:<code>qinterp(<var>dx</var><sub>scalar</sub>, <var>y</var>, <var>ip</var> {, <var>nwidth</var>})</code> | |||
:;<var>dx<var>:distance bewteen x values, <code>x[i] = ''dx'' * i</code> | |||
:;<var>x<var>:x data vector | |||
:;<var>y</var>:y data vector: <code>y[i] = f(x[i])</code>. | |||
:;<var>ip</var>: a scalar or vector containing the indices of local maxima | |||
:;<var>nwidth</var>: the width to be used for interpolation | |||
;Result: A vector ''r'' with 2 elements (''r''[0] = xpeak, ''r[1]'' = ypeak) or a matrix with two rows (''r''[0,j] = xpeak<sub>j</sub>, ''r[1,j]'' = ypeak<sub>j</sub>) containing the interpolated coordinates of the local maxima (peaks). For the 2nd order (parabolic) interpolation the (x,y) points at ''ip-npeaks'', ''ip'' and ''ip+npeask'' are used. | |||
;See also: [[Programmer_Guide/Command_Reference/EVAL/ipeak|ipeak]], [[Programmer_Guide/Command_Reference/EVAL/formants|formants]] | |||
[[Programmer_Guide/Command_Reference/EVAL#Functions|<function list>]] | |||
{{DISPLAYTITLE:{{SUBPAGENAME}}}} | {{DISPLAYTITLE:{{SUBPAGENAME}}}} | ||
=====qinterp===== | =====qinterp===== | ||
Revision as of 10:25, 11 April 2011
Compute interploated coordinates of local peaks of a function using 2nd order interpolation.
- Usage
qinterp(dxscalar, y, ip {, nwidth})qinterp(dxscalar, y, ip {, nwidth})- dx:distance bewteen x values,
x[i] = dx * i - x:x data vector
- y
- y data vector:
y[i] = f(x[i]). - ip
- a scalar or vector containing the indices of local maxima
- nwidth
- the width to be used for interpolation
- dx:distance bewteen x values,
- Result
- A vector r with 2 elements (r[0] = xpeak, r[1] = ypeak) or a matrix with two rows (r[0,j] = xpeakj, r[1,j] = ypeakj) containing the interpolated coordinates of the local maxima (peaks). For the 2nd order (parabolic) interpolation the (x,y) points at ip-npeaks, ip and ip+npeask are used.
qinterp
Lays a parabola through three points around each peak value and calculates the interpolated peak. The result is a one or two row vector or matrix.
Usage:
qinterp(x, y, ipeak, nwidth)
Parameters:
- x
- The number for x[i] = i*number or the x-scale vector.
- y
- The data vector (function).
- ipeak
- The indices of the peak values or the center of the interpolation.
- nwidth
- The width of the interpolation. The default is
1.
Return Type:
vector or matrix
Result:
row 1 = xpeak[]
row 2 = ypeak[]
